You can create categories to group your contacts, tasks, and memos. You can also narrow the contacts, tasks, and memos that appear based on categories.
Category names are not case sensitive. More than one category can apply to a contact, task, or memo. If you use IBM® Lotus Notes®, you can apply more than one category to a task on your BlackBerry® device, but only one category synchronizes with the task in Lotus Notes.
Categories are shared between the contact list, the task list, and the memo list and changes that you make in one application are made in all applications.